EP3315841B1 - Reduction of microbiological growth in pipes - Google Patents
Reduction of microbiological growth in pipes Download PDFInfo
- Publication number
- EP3315841B1 EP3315841B1 EP16196711.2A EP16196711A EP3315841B1 EP 3315841 B1 EP3315841 B1 EP 3315841B1 EP 16196711 A EP16196711 A EP 16196711A EP 3315841 B1 EP3315841 B1 EP 3315841B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- pipe
- inner layer
- electrical connector
- electric current
- liquid
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Links
- 230000002906 microbiologic effect Effects 0.000 title claims description 47
- 239000007788 liquid Substances 0.000 claims description 51
- -1 polyethylene Polymers 0.000 claims description 16
- 239000002861 polymer material Substances 0.000 claims description 14
- 239000004698 Polyethylene Substances 0.000 claims description 12
- 229920000573 polyethylene Polymers 0.000 claims description 12
- 235000019241 carbon black Nutrition 0.000 claims description 10
- 239000006229 carbon black Substances 0.000 claims description 10
- 229920001940 conductive polymer Polymers 0.000 claims description 8
- 238000000034 method Methods 0.000 claims description 8
- 238000009420 retrofitting Methods 0.000 claims description 3
- 239000010410 layer Substances 0.000 description 55
- 235000013361 beverage Nutrition 0.000 description 17
- 235000013405 beer Nutrition 0.000 description 11
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 11
- 238000004064 recycling Methods 0.000 description 9
- 239000002356 single layer Substances 0.000 description 8
- 239000000463 material Substances 0.000 description 6
- 230000015572 biosynthetic process Effects 0.000 description 5
- 239000004952 Polyamide Substances 0.000 description 4
- 239000004743 Polypropylene Substances 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 238000011835 investigation Methods 0.000 description 4
- 229920002647 polyamide Polymers 0.000 description 4
- 229920000728 polyester Polymers 0.000 description 4
- 229920000642 polymer Polymers 0.000 description 4
- 229920001155 polypropylene Polymers 0.000 description 4
- 241000894006 Bacteria Species 0.000 description 3
- 235000009508 confectionery Nutrition 0.000 description 3
- 238000009434 installation Methods 0.000 description 3
- 238000005259 measurement Methods 0.000 description 3
- 238000004140 cleaning Methods 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 238000010079 rubber tapping Methods 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 241000589248 Legionella Species 0.000 description 1
- 208000007764 Legionnaires' Disease Diseases 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 239000002173 cutting fluid Substances 0.000 description 1
- 235000013365 dairy product Nutrition 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- 229910021389 graphene Inorganic materials 0.000 description 1
- 238000003780 insertion Methods 0.000 description 1
- 230000037431 insertion Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000005555 metalworking Methods 0.000 description 1
- 239000008267 milk Substances 0.000 description 1
- 235000013336 milk Nutrition 0.000 description 1
- 210000004080 milk Anatomy 0.000 description 1
- 239000002071 nanotube Substances 0.000 description 1
- 235000008935 nutritious Nutrition 0.000 description 1
- 244000052769 pathogen Species 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
- 230000003442 weekly effect Effects 0.000 description 1
Images
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
- F16L58/00—Protection of pipes or pipe fittings against corrosion or incrustation
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
- A61L2/00—Methods or apparatus for disinfecting or sterilising materials or objects other than foodstuffs or contact lenses; Accessories therefor
- A61L2/02—Methods or apparatus for disinfecting or sterilising materials or objects other than foodstuffs or contact lenses; Accessories therefor using physical phenomena
- A61L2/03—Electric current
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
- F16L11/00—Hoses, i.e. flexible pipes
- F16L11/04—Hoses, i.e. flexible pipes made of rubber or flexible plastics
- F16L11/12—Hoses, i.e. flexible pipes made of rubber or flexible plastics with arrangements for particular purposes, e.g. specially profiled, with protecting layer, heated, electrically conducting
- F16L11/127—Hoses, i.e. flexible pipes made of rubber or flexible plastics with arrangements for particular purposes, e.g. specially profiled, with protecting layer, heated, electrically conducting electrically conducting
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
- F16L9/00—Rigid pipes
- F16L9/12—Rigid pipes of plastics with or without reinforcement
- F16L9/125—Rigid pipes of plastics with or without reinforcement electrically conducting
Definitions
- the proposed technology generally relates to the field of liquid transportation, dispensing, and recycling. In particular, it relates to the reduction of microbiological growth in pipes.
- Microbiological growth and the formation of biofilms on the inside of pipes is a concern in many applications where a liquid is conveyed. Properties of the liquid as such can be influenced by the microbiological growth and make it less suitable for its intended use. Microbiological growth in a pipe may also increase microbiological growth further downstream in equipment that is routinely cleaned from such growth. Microbiological growth can also detach from inside a pipe and cause clogging or damage in downstream equipment. It is also a known problem that microbiological growth on the inside of a pipe can introduce harmful pathogens in the conveyed liquid.
- liquid transportation is water supply by public utilities.
- the pipes are used for long periods of time, typically stretching over several decades. Large quantities of microbiological material can build up in the pipes, which reduces the transport capacity of the pipes.
- the transport may be over shorter distances, such as in dairy equipment at milk farms.
- Examples of applications using liquid recycling where microbiological growth can be a problem are numerous. For example, it may be a problem in centralized domestic cooling of buildings, recycling of washing liquids in car washes, recycling of cutting fluids in metalworking, recycling of liquids in paper mills, and circulating low-temperature heating systems in buildings.
- liquid dispensing applications are also numerous.
- the microbiological growth may be a problem in beverage dispensing, in particular in dispensing of beer from kegs, in dental equipment, and in domestic water systems, such as showers.
- the latter is a known source of legionella, which may be harmful to people.
- AT 506089A4 discloses a system for preventing microbiological growth in a conduit conveying a liquid, wherein the system comprises: a multi-layered pipe constituting said conduit and having an inner layer and an outer layer, wherein the inner layer covers the complete inside of the pipe and is formed of an electrically conductive polymer material, wherein a liquid in the pipe is in direct contact with the inner layer.
- microbiological growth is understood to encompass the formation of a biofilm.
- microbiological growth may be colonies of bacteria.
- a system for preventing microbiological growth and/or the formation of a biofilm in a conduit conveying a liquid comprises a multi-layered pipe constituting said conduit and having an inner layer and an outer layer.
- the inner layer covers the complete inside of the pipe and is formed of an electrically conductive polymer material, wherein a liquid in the pipe is in direct contact with the inner layer.
- the outer layer covers at least a portion of the outside of the inner layer and is formed of an electrically insulating polymer material.
- the system further comprises a first electrical connector connecting to the inner layer from outside the pipe and a second electrical connector connecting to the inner layer from outside the pipe, wherein the first electrical connector (19) and the second electrical connector (19) are spaced apart along the pipe.
- the system also comprises an electric power source operationally connected to the first electrical connector and the second electrical connector and configured for supplying an electric current to the inner layer.
- the multilayered pipe may be a rigid pipe or a flexible hose.
- a method for retrofitting a system for preventing microbiological growth in an existing conduit for conveying a liquid.
- the method comprises: providing a system according to the first aspect, and providing the pipe of the system inside the existing conduit.
- the above object is achieved by a method for preventing microbiological growth in the pipe of a system according to the first aspect, wherein the pipe conveys a liquid.
- the method comprises: supplying an electric current to the inner layer of the pipe with the electric power source.
- a liquid is in direct contact with the inner layer means that there is no other material between the inner layer and the liquid.
- the electric current supplied to the inner layer or single layer may be a direct current.
- the direct current may be below 10 mA, below 1 mA, between 0.1 mA and 1 mA, or between 0.3 mA and 0.7 mA.
- the electric current may be generated at a voltage between the first electrical connector and the second electrical connector that is below 150 V, below 120 V, between 20 V and 100 V, or between 50 V and 70 V.
- the power supply may be configured to supply the direct current to the first electrical connector or the second electrical connector at the here listed voltages between the first electrical connector and the second electrical connector. It has been found that the operating parameters described here reduce microbiological growth, in particular in fast flowing sweet water in distribution mains.
- the electric current supplied to the inner layer or single layer may be an alternating current.
- the alternating current may be below 10 mA, below 1 mA, between 0.1 mA and 1 mA, or between 0.4 mA and 0.8 mA.
- the alternating current may be supplied at a voltage between the first electrical connector and the second electrical connector that is below 80 V, below 50 V, between 10 V and 50 V, between 20 V and 50 V, or between 30 V and 50 V.
- the power supply may be configured to supply the alternating current to the first electrical connector or the second electrical connector at the here listed voltages between the first electrical connector and the second electrical connector.
- the alternating current may have a frequency between 1 kHz and 5 kHz, or between 1 kHz and 2 kHz. It has been found that the operating parameters described here reduce microbiological growth, in particular in slowly flowing or still sweet water in distribution mains.
- the power source may be further configured for supplying a pulsed electric current, both for direct current and alternating current.
- the pulses may have combined pulse length over a period of time that is equal to or less than 50% of the length of the period. It has been found that the microbiological growth is reduced also for pulsed electric currents. The pulsing has the effect of reduced power consumptions, which contributes to lower operation costs.
- the electric current may be supplied at a voltage between the first electrical connector and the second electrical connector that is in the range 1 V and 10 V, 2 V and 8 V, or 3 V and 6. It is contemplated that these voltages will have a sufficient effect on the microbiological growth.
- the electric current supplied to the inner layer or single layer may be a direct current or an alternating current below 10 mA, below 1 mA, between 0.1 mA and 1 mA, or between 0.4 mA and 0.8 mA. Additionally, the electric current may be supplied at a voltage between the first electrical connector and the second electrical connector that is in the range 0.5 kV and 6 kV, 0.5 kV and 4 kV, 0.5 kV and 2 kV, or 0.5 kV and 1 kV. Additionally or alternatively, the electric current may be pulsed.
- the pulses of the electric current may have a pulse length in the range 1 ms and 500 ms, 1 ms and 100 ms, or 1 ms and 10 ms. It is contemplated that these operation parameter will have a significant effect on the microbiological growth.
- the electrically conductive polymer material of the inner layer or the single layer may be a carbon-black filled polymer. Additionally or alternatively to carbon-black, the polymer may be filled with nanotubes, graphene, and/or metal fibers or filaments for providing the electrical conductivity. These materials typically have the advantage that a smaller amount of the material is required than for carbon-black for achieving a desired electrical conductivity.
- the electrically conductive polymer material may comprise or be composed of polyethylene, polypropylene, polyamide, or polyester.
- the polymer material of the electrically insulating polymer material, i.e. the outer layer may comprise or be composed of polyethylene, polypropylene, polyamide, or polyester.
- the electrically conductive polymer material may comprise or be composed of polyethylene, polypropylene, polyamide, or polyester.
- the polymer material of the electrically insulating polymer material, i.e. the outer layer may comprise or be composed of polyethylene, polypropylene, polyamide, or polyesters.
- Carbon black as such may contribute to an increased microbiological growth on the inside of the pipe or hose in the absence of an electric current. However, together with the electric current in the inner layer or single layer, it has been shown that the net effect will be a reduced microbiological growth.
- a multi-layered pipe 10 is provided having an inner layer 12 and an outer layer 14.
- the inner layer 12 is composed of carbon-black filled polyethylene with a 20 weight percentage of carbon-black.
- the outer layer is composed of polyethylene. This means that the inner layer 12 is electrically conductive and the outer layer 14 is electrically insulating.
- the inner layer 12 and the outer layer 14 have been co-extruded in a manner such that the inner layer 12 covers the complete inside 16 of the pipe 10 and the outer layer 14 covers the complete outside of the inner pipe 12, as is shown in Fig. 1c . There is no material between the inner pipe 12 and a liquid conveyed by the pipe 10.
- the polymer of the inner layer 12 and the outer layer 14 is polyethylene, which means that the pipe 10 will have the properties of a hose with respect to manual handling.
- the outer layer 14 is removed at the ends of the pipe 10, thereby making the inner layer 12 accessible from outside the pipe 10, as is shown in Fig. 1b .
- the outer layer 14 is removed at other parts of the pipe 10, for example further in from the ends of the pipes, thus leaving the inner layer 12 covered by the outer layer 14 at the ends of the pipe 10.
- a first electrical connector 18 is attached to the exposed inner layer 12 at one end of the pipe 10, and a second electrical connector 19 is attached to the exposed inner layer 12 at the other end of the pipe 10. Both connectors are tightened around the inner layer in a similar manner as a hose clamp is tightened, thus ensuring a good electrical connection between each of the connectors and the inner layer 12.
- An electric power source 20 is provided that is operationally connected to the first connector 18 via a first cable 22 and to the second connector 19 via a second cable 24.
- the electric power source 20 When installed in an application and with a liquid running through the pipe 10, the electric power source 20 is set to supply a direct current in the inner layer 12 that is between 0.3 mA and 0.7 mA by way of the electric circuit established with the first connector 18, the second connector 19, the first cable 22, and the second cable 24.
- the electric power source 20 is also set to generate a stable potential in the range 50 V and 70 V between the first connector 18 and the second connector 19.
- the electric power source 20 is set to supply an alternating current in the inner layer 12 that is between 0.4 mA and 0.8 mA. Additionally or alternatively, the electric power source 20 is also set to generate a stable potential in the range 50 V and 70 V between the first connector 18 and the second connector 19.
- the electric power source 20 is operated to supply a continuous electric current to the inner layer 12.
- the electric current is pulsed or intermittently operated.
- the electric current is supplied in a cycle alternating between one week of electric current supply and one week without electric current supply, thus effectively having a combined pulse length over a period of time that is 50% of the length of the period.
- FIG. 2 An embodiment of the proposed system 8 is shown in Fig. 2 .
- the system 8 is installed in a liquid transportation application 40. It has all the features of the system 8 described above in relation to Fig. 1 .
- the pipe 10 is connected to a liquid supply 26, for example public water mains.
- the pipe 10 is connected to a liquid recipient 28, such as the water inlet at a domestic or industrial building, or another section of the public water mains.
- Fig. 3 schematically illustrates an embodiment of the proposed system 8 in a liquid dispensing application.
- the system 8 has all the features described above in relation to Fig. 1 .
- the pipe 10 is connected to a liquid supply 30, for example a hot-water pipe in a domestic building.
- the pipe 10 is connected to a liquid dispenser 32, such as a shower in a domestic or public building.
- FIG. 4 Another embodiment of the proposed system 8 is shown in Fig. 4 .
- the system 8 is installed in a liquid recycling application 44. It has all the features of the system 8 described above in relation to Fig. 1 .
- the pipe 10 is connected to liquid recycler 28, such as the heat exchanger, the circulation pump, and the radiators of a low-temperature heating system of a building.
- FIG. 5 An embodiment of a beverage dispensing system 6 is schematically illustrated in Fig. 5 .
- the dispensing system 6 has a liquid dispenser or tapping station for the beverage in the form of a beer tap 32 attached to a bar counter 34. It further has a beverage conduit 36 for conveying a beverage from a liquid supply or container containing the beverage in the form of a beer keg 30.
- a system 8 for preventing microbiological growth having the features of the embodiment described above in relation to Fig. 1 forms part of the dispensing system 6.
- the pipe 10 constitutes a portion of the beverage conduit 6. At one end, the pipe 10 is connected to the beer keg 30 via a beverage hose 37. At its other end, the pipe 10 is connected to the beer tap 32.
- the electric power source 20 is operated as described above in relation to Fig. 1 , microbiological growth is prevented in the pipe 10.
- FIG. 6 Another embodiment of a beverage dispensing system 6 is schematically illustrated in Fig. 6 .
- the dispensing system 6 has a liquid dispenser or tapping station for the beverage in the form of a beer tap 32 attached to a bar counter 34.
- a system 8 for preventing microbiological growth forms part of the dispensing system 6.
- the system 8 differs in that the pipe 10 is a hose.
- the dispensing system 6 has an existing conduit 38 in the form of a rigid pipe 38.
- the hose 10 has been retrofitted in the rigid pipe 38 by the insertion of the hose 10 through the receiving end of the rigid pipe 38 and by connecting the hose 10 to the beer tap 32.
- the hose 10 is connected to a beer keg 30 via a beverage hose 37.
- the hose 10 forms part of a beverage conduit 36 conveying beer from the keg 30 to the beer tap 32.
- the investigation was divided into two periods, the first period covering weeks 1 to 10 and the second period covering weeks 10 to 25.
- Microbiological growth was monitored weekly by the taking of samples of the biofilm from the inner walls of the pipes. The samples were cultivated for 48 hours and the number of bacteria colonies was then calculated in each sample and used to represent the microbiological growth in the corresponding setup.
- the microbiological growth was allowed to settle on the inner walls and allowed to adjust to the environment inside the pipes. No conclusive results were achieved in the first period. The three setups were then moved and connected to the public mains at another point before the second period of investigation started.
- the results of the second period are shown in Fig. 7 .
- the weeks are indicated on the abscissa and the number of counted bacteria is indicated on the ordinate.
- the left bar represents the measurement from the first setup, i.e. with a single layer polyethylene pipe
- the middle bar represents the measurement from the second setup, i.e. with an inner conductive layer without an electric current
- the right bar represents the measurement from the third setup, i.e. with an inner conductive layer with an electric current. It should be noted that no sampling was performed in the weeks without any bars.
- the microbiological growth in the second setup was greater than in the third setup, thus showing that the supplied electric current reduces the microbiological growth. It is contemplated that the high initial counts of the second and third setups is a result of an initial adaption to the environment inside the pipes with carbon-black in the inner layer.
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- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Health & Medical Sciences (AREA)
- Epidemiology (AREA)
- Life Sciences & Earth Sciences (AREA)
- Animal Behavior & Ethology (AREA)
- General Health & Medical Sciences (AREA)
- Public Health (AREA)
- Veterinary Medicine (AREA)
- Rigid Pipes And Flexible Pipes (AREA)
- Water Treatment By Electricity Or Magnetism (AREA)
Description
- The proposed technology generally relates to the field of liquid transportation, dispensing, and recycling. In particular, it relates to the reduction of microbiological growth in pipes.
- Microbiological growth and the formation of biofilms on the inside of pipes is a concern in many applications where a liquid is conveyed. Properties of the liquid as such can be influenced by the microbiological growth and make it less suitable for its intended use. Microbiological growth in a pipe may also increase microbiological growth further downstream in equipment that is routinely cleaned from such growth. Microbiological growth can also detach from inside a pipe and cause clogging or damage in downstream equipment. It is also a known problem that microbiological growth on the inside of a pipe can introduce harmful pathogens in the conveyed liquid.
- Three groups of applications where microbiological growth in a pipe can be a problem have been identified, namely liquid transportation, liquid recycling, and liquid dispensing.
- An example of liquid transportation is water supply by public utilities. The pipes are used for long periods of time, typically stretching over several decades. Large quantities of microbiological material can build up in the pipes, which reduces the transport capacity of the pipes. The transport may be over shorter distances, such as in dairy equipment at milk farms.
- Examples of applications using liquid recycling where microbiological growth can be a problem are numerous. For example, it may be a problem in centralized domestic cooling of buildings, recycling of washing liquids in car washes, recycling of cutting fluids in metalworking, recycling of liquids in paper mills, and circulating low-temperature heating systems in buildings.
- Examples of liquid dispensing applications are also numerous. The microbiological growth may be a problem in beverage dispensing, in particular in dispensing of beer from kegs, in dental equipment, and in domestic water systems, such as showers. The latter is a known source of legionella, which may be harmful to people.
- Pipes used in the handling of nutritious liquids, such as beer, require frequent cleaning, in particular if the transported liquids are stored at room temperature and cooled first at the dispensing point. This may cause rapid microbiological growth in the pipe conveying the liquids. It is known to cool such pipes to reduce the microbiological growth and prevent deterioration of the conveyed liquids. However, such a technology is typically costly to install and operate.
-
AT 506089A4 - The cleaning of a pipe is often costly, both in itself and due to interruptions in the operation of the application. It also often requires the pipe to be flushed afterwards, which is not practical in many applications, such as in closed circulation systems and long distance water transportation.
- There is a need for pipes in which microbiological growth and the formation of biofilms is reduced. Further, there is a need for pipes that have low installation and operation costs with respect to the prevention of microbiological growth. Replacing pipes in an existing application may be a costly operation. Thus, there is also a need for pipes preventing microbiological growth that can be retrofitted in an existing application.
- Throughout these specifications, microbiological growth is understood to encompass the formation of a biofilm. For example, microbiological growth may be colonies of bacteria.
- It is an object of the proposed technology to meet one or more of the abovementioned needs. In a first aspect, this is achieved by a system for preventing microbiological growth and/or the formation of a biofilm in a conduit conveying a liquid. The system comprises a multi-layered pipe constituting said conduit and having an inner layer and an outer layer. The inner layer covers the complete inside of the pipe and is formed of an electrically conductive polymer material, wherein a liquid in the pipe is in direct contact with the inner layer. The outer layer covers at least a portion of the outside of the inner layer and is formed of an electrically insulating polymer material. The system further comprises a first electrical connector connecting to the inner layer from outside the pipe and a second electrical connector connecting to the inner layer from outside the pipe, wherein the first electrical connector (19) and the second electrical connector (19) are spaced apart along the pipe. The system also comprises an electric power source operationally connected to the first electrical connector and the second electrical connector and configured for supplying an electric current to the inner layer. The multilayered pipe may be a rigid pipe or a flexible hose.
- In a second aspect, a method is provided for retrofitting a system for preventing microbiological growth in an existing conduit for conveying a liquid. The method comprises: providing a system according to the first aspect, and providing the pipe of the system inside the existing conduit.
- In a third aspect, the above object is achieved by a method for preventing microbiological growth in the pipe of a system according to the first aspect, wherein the pipe conveys a liquid. The method comprises: supplying an electric current to the inner layer of the pipe with the electric power source.
- Here, and throughout these specifications, that a liquid is in direct contact with the inner layer means that there is no other material between the inner layer and the liquid.
- It has been found that when a current is supplied to the inner layer or single layer, microbiological growth and formation of biofilms are significantly reduced. There is no established theory for why this happens, but a proof-of-concept is provided below. Further, the required electric power for operating the proposed systems is low, thus contributing to low operation costs. Further, the fact that the pipes are made of polymer-based materials means that the manufacturing costs are typically low, thus contributing to lower installation costs. A hose allows for a retrofitting inside existing pipes, which also contributes to lower installation costs.
- Further optional features of the different aspects of the proposed technology are presented below.
- The electric current supplied to the inner layer or single layer may be a direct current. The direct current may be below 10 mA, below 1 mA, between 0.1 mA and 1 mA, or between 0.3 mA and 0.7 mA. The electric current may be generated at a voltage between the first electrical connector and the second electrical connector that is below 150 V, below 120 V, between 20 V and 100 V, or between 50 V and 70 V. The power supply may be configured to supply the direct current to the first electrical connector or the second electrical connector at the here listed voltages between the first electrical connector and the second electrical connector. It has been found that the operating parameters described here reduce microbiological growth, in particular in fast flowing sweet water in distribution mains.
- Alternatively, the electric current supplied to the inner layer or single layer may be an alternating current. The alternating current may be below 10 mA, below 1 mA, between 0.1 mA and 1 mA, or between 0.4 mA and 0.8 mA. The alternating current may be supplied at a voltage between the first electrical connector and the second electrical connector that is below 80 V, below 50 V, between 10 V and 50 V, between 20 V and 50 V, or between 30 V and 50 V. The power supply may be configured to supply the alternating current to the first electrical connector or the second electrical connector at the here listed voltages between the first electrical connector and the second electrical connector. The alternating current may have a frequency between 1 kHz and 5 kHz, or between 1 kHz and 2 kHz. It has been found that the operating parameters described here reduce microbiological growth, in particular in slowly flowing or still sweet water in distribution mains.
- The power source may be further configured for supplying a pulsed electric current, both for direct current and alternating current. The pulses may have combined pulse length over a period of time that is equal to or less than 50% of the length of the period. It has been found that the microbiological growth is reduced also for pulsed electric currents. The pulsing has the effect of reduced power consumptions, which contributes to lower operation costs.
- Alternatively to the abovementioned voltages at which the direct current and the alternating current are supplied, the electric current may be supplied at a voltage between the first electrical connector and the second electrical connector that is in the
range 1 V and 10 V, 2 V and 8 V, or 3 V and 6. It is contemplated that these voltages will have a sufficient effect on the microbiological growth. - Alternatively, the electric current supplied to the inner layer or single layer may be a direct current or an alternating current below 10 mA, below 1 mA, between 0.1 mA and 1 mA, or between 0.4 mA and 0.8 mA. Additionally, the electric current may be supplied at a voltage between the first electrical connector and the second electrical connector that is in the range 0.5 kV and 6 kV, 0.5 kV and 4 kV, 0.5 kV and 2 kV, or 0.5 kV and 1 kV. Additionally or alternatively, the electric current may be pulsed. Further, the pulses of the electric current may have a pulse length in the range 1 ms and 500 ms, 1 ms and 100 ms, or 1 ms and 10 ms. It is contemplated that these operation parameter will have a significant effect on the microbiological growth.
- The electrically conductive polymer material of the inner layer or the single layer may be a carbon-black filled polymer. Additionally or alternatively to carbon-black, the polymer may be filled with nanotubes, graphene, and/or metal fibers or filaments for providing the electrical conductivity. These materials typically have the advantage that a smaller amount of the material is required than for carbon-black for achieving a desired electrical conductivity.
- In the case of a pipe, the electrically conductive polymer material may comprise or be composed of polyethylene, polypropylene, polyamide, or polyester. The polymer material of the electrically insulating polymer material, i.e. the outer layer, may comprise or be composed of polyethylene, polypropylene, polyamide, or polyester. In the case of a hose, the electrically conductive polymer material may comprise or be composed of polyethylene, polypropylene, polyamide, or polyester. The polymer material of the electrically insulating polymer material, i.e. the outer layer may comprise or be composed of polyethylene, polypropylene, polyamide, or polyesters.
- Carbon black as such may contribute to an increased microbiological growth on the inside of the pipe or hose in the absence of an electric current. However, together with the electric current in the inner layer or single layer, it has been shown that the net effect will be a reduced microbiological growth.
- A more complete understanding of the proposed technology and other features and advantages of the proposed technology, will be apparent from the following detailed description of the figures, where:
- Figs. 1a-c
- schematically illustrate the a setup of an embodiment of the proposed system,
- Fig. 2
- schematically illustrates an embodiment of the proposed system in a liquid transportation application,
- Fig. 3
- schematically illustrates an embodiment of the proposed system in a liquid dispensing application,
- Fig. 4
- schematically illustrates an embodiment of the proposed system in a liquid recycling application,
- Fig. 5
- schematically illustrates an embodiment of a beverage dispensing system including the proposed system for preventing microbiological growth,
- Fig. 6
- schematically illustrates an embodiment of a beverage dispensing system including a retrofitted proposed system for preventing microbiological growth, and
- Fig. 7
- is a graph illustrating the results of an investigation of the function of the proposed technology.
- The setup of an embodiment of a system for reducing microbiological growth in a conduit is schematically illustrated in
Figs. 1a-c . Amulti-layered pipe 10 is provided having aninner layer 12 and anouter layer 14. Theinner layer 12 is composed of carbon-black filled polyethylene with a 20 weight percentage of carbon-black. The outer layer is composed of polyethylene. This means that theinner layer 12 is electrically conductive and theouter layer 14 is electrically insulating. Theinner layer 12 and theouter layer 14 have been co-extruded in a manner such that theinner layer 12 covers the complete inside 16 of thepipe 10 and theouter layer 14 covers the complete outside of theinner pipe 12, as is shown inFig. 1c . There is no material between theinner pipe 12 and a liquid conveyed by thepipe 10. - In an alternative embodiment, the polymer of the
inner layer 12 and theouter layer 14 is polyethylene, which means that thepipe 10 will have the properties of a hose with respect to manual handling. - The
outer layer 14 is removed at the ends of thepipe 10, thereby making theinner layer 12 accessible from outside thepipe 10, as is shown inFig. 1b . In alternative embodiments, theouter layer 14 is removed at other parts of thepipe 10, for example further in from the ends of the pipes, thus leaving theinner layer 12 covered by theouter layer 14 at the ends of thepipe 10. - A first
electrical connector 18 is attached to the exposedinner layer 12 at one end of thepipe 10, and a secondelectrical connector 19 is attached to the exposedinner layer 12 at the other end of thepipe 10. Both connectors are tightened around the inner layer in a similar manner as a hose clamp is tightened, thus ensuring a good electrical connection between each of the connectors and theinner layer 12. - An
electric power source 20 is provided that is operationally connected to thefirst connector 18 via afirst cable 22 and to thesecond connector 19 via asecond cable 24. When installed in an application and with a liquid running through thepipe 10, theelectric power source 20 is set to supply a direct current in theinner layer 12 that is between 0.3 mA and 0.7 mA by way of the electric circuit established with thefirst connector 18, thesecond connector 19, thefirst cable 22, and thesecond cable 24. In an alternative embodiment, theelectric power source 20 is also set to generate a stable potential in the range 50 V and 70 V between thefirst connector 18 and thesecond connector 19. - In alternative embodiments, the
electric power source 20 is set to supply an alternating current in theinner layer 12 that is between 0.4 mA and 0.8 mA. Additionally or alternatively, theelectric power source 20 is also set to generate a stable potential in the range 50 V and 70 V between thefirst connector 18 and thesecond connector 19. - The
electric power source 20 is operated to supply a continuous electric current to theinner layer 12. In an alternative embodiment, the electric current is pulsed or intermittently operated. In one embodiment, the electric current is supplied in a cycle alternating between one week of electric current supply and one week without electric current supply, thus effectively having a combined pulse length over a period of time that is 50% of the length of the period. - An embodiment of the proposed
system 8 is shown inFig. 2 . Thesystem 8 is installed in aliquid transportation application 40. It has all the features of thesystem 8 described above in relation toFig. 1 . At one end, thepipe 10 is connected to aliquid supply 26, for example public water mains. At the other end, thepipe 10 is connected to aliquid recipient 28, such as the water inlet at a domestic or industrial building, or another section of the public water mains. -
Fig. 3 schematically illustrates an embodiment of the proposedsystem 8 in a liquid dispensing application. Thesystem 8 has all the features described above in relation toFig. 1 . At one end, thepipe 10 is connected to aliquid supply 30, for example a hot-water pipe in a domestic building. At the other end, thepipe 10 is connected to aliquid dispenser 32, such as a shower in a domestic or public building. - Another embodiment of the proposed
system 8 is shown inFig. 4 . Thesystem 8 is installed in a liquid recycling application 44. It has all the features of thesystem 8 described above in relation toFig. 1 . At both its ends thepipe 10 is connected toliquid recycler 28, such as the heat exchanger, the circulation pump, and the radiators of a low-temperature heating system of a building. - An embodiment of a
beverage dispensing system 6 is schematically illustrated inFig. 5 . Thedispensing system 6 has a liquid dispenser or tapping station for the beverage in the form of abeer tap 32 attached to abar counter 34. It further has abeverage conduit 36 for conveying a beverage from a liquid supply or container containing the beverage in the form of abeer keg 30. Asystem 8 for preventing microbiological growth having the features of the embodiment described above in relation toFig. 1 forms part of thedispensing system 6. Thepipe 10 constitutes a portion of thebeverage conduit 6. At one end, thepipe 10 is connected to thebeer keg 30 via abeverage hose 37. At its other end, thepipe 10 is connected to thebeer tap 32. When theelectric power source 20 is operated as described above in relation toFig. 1 , microbiological growth is prevented in thepipe 10. - Another embodiment of a
beverage dispensing system 6 is schematically illustrated inFig. 6 . Thedispensing system 6 has a liquid dispenser or tapping station for the beverage in the form of abeer tap 32 attached to abar counter 34. Asystem 8 for preventing microbiological growth, having the features of the embodiment described in relation toFig. 1 , forms part of thedispensing system 6. However, thesystem 8 differs in that thepipe 10 is a hose. Thedispensing system 6 has an existingconduit 38 in the form of arigid pipe 38. Thehose 10 has been retrofitted in therigid pipe 38 by the insertion of thehose 10 through the receiving end of therigid pipe 38 and by connecting thehose 10 to thebeer tap 32. At one end, thehose 10 is connected to abeer keg 30 via abeverage hose 37. Thus, thehose 10 forms part of abeverage conduit 36 conveying beer from thekeg 30 to thebeer tap 32. When theelectric power source 20 is operated as described above in relation toFig. 1 , microbiological growth is prevented in thehose 10. - An investigation of the proposed technology has been performed including three different setups. Three pipes of identical length and diameter were used. The length was 25 meter and the inner diameter was 63 mm. In the first setup, the pipe was a single-layer polyethylene pipe. In the second and third setups the pipes were identical multi-layered pipes with an inner layer of carbon-black-filled polyethylene. Electrical connectors were attached to the inner layer of the pipes at the ends of the pipes. Sweet water from public water mains was introduced in and allowed to flow through the pipes. An electric current of 0.5 mA was supplied to the electrical connectors of the third setup at a voltage in the range 60 V to 65 V.
- The investigation was divided into two periods, the first period covering weeks 1 to 10 and the second
period covering weeks 10 to 25. - Microbiological growth was monitored weekly by the taking of samples of the biofilm from the inner walls of the pipes. The samples were cultivated for 48 hours and the number of bacteria colonies was then calculated in each sample and used to represent the microbiological growth in the corresponding setup.
- In the first period, the microbiological growth was allowed to settle on the inner walls and allowed to adjust to the environment inside the pipes. No conclusive results were achieved in the first period. The three setups were then moved and connected to the public mains at another point before the second period of investigation started.
- The results of the second period are shown in
Fig. 7 . The weeks are indicated on the abscissa and the number of counted bacteria is indicated on the ordinate. For each week, the left bar represents the measurement from the first setup, i.e. with a single layer polyethylene pipe, the middle bar represents the measurement from the second setup, i.e. with an inner conductive layer without an electric current, and the right bar represents the measurement from the third setup, i.e. with an inner conductive layer with an electric current. It should be noted that no sampling was performed in the weeks without any bars. - As can be clearly seen in
Fig. 7 , afterweek 16 when the microbiological growth had established itself in the pipes, the microbiological growth in the second setup was greater than in the third setup, thus showing that the supplied electric current reduces the microbiological growth. It is contemplated that the high initial counts of the second and third setups is a result of an initial adaption to the environment inside the pipes with carbon-black in the inner layer. -
- 6
- beverage dispensing system
- 8
- system
- 10
- pipe or hose
- 12
- inner layer
- 14
- outer layer
- 16
- inside of the pipe
- 18
- first electrical connector
- 19
- second electrical connector
- 20
- electric power source
- 22
- first cable
- 24
- second cable
- 26
- liquid supply
- 28
- liquid recipient
- 30
- liquid supply
- 32
- liquid dispenser
- 34
- bar counter
- 36
- a beverage conduit
- 37
- beverage hose
- 38
- existing conduit
- 40
- liquid transportation application
- 42
- liquid dispensing application
- 44
- liquid recycling application
Claims (15)
- A system (8) for preventing microbiological growth in a conduit conveying a liquid, wherein the system (8) comprises:- a multi-layered pipe (10) constituting said conduit and having an inner layer (12) and an outer layer (14), wherein the inner layer (12) covers the complete inside (16) of the pipe (10) and is formed of an electrically conductive polymer material, wherein a liquid in the pipe (10) is in direct contact with the inner layer (12), and wherein the outer layer (14) covers at least a portion of the outside of the inner layer (12) and is formed of an electrically insulating polymer material,Characterised by- a first electrical connector (18) connecting to the inner layer (12) from outside the pipe (10) and a second electrical connector (19) connecting to the inner layer (12) from outside the pipe (10), wherein the first electric connector (18) and the second electric connector (19) are spaced apart along the pipe (10), and- an electric power source (20) operationally connected to the first electrical connector (18) and the second electrical connector (19) and configured for supplying an electric current to the inner layer (12).
- The system (8) according to claim 1, wherein the electric current is a direct current.
- The system (8) according to claim 2, wherein the electric current is below 10 mA, below 1 mA, between 0.1 mA and 1 mA, or between 0.3 mA and 0.7 mA.
- The system (8) according to claim 2 or 3, wherein the electric current is supplied at a voltage between the first electrical connector (18) and the second electrical connector (19) that is below 150 V, below 120 V, between 20 V and 100 V, or between 50 V and 70 V.
- The system (8) according to claim 1, wherein the electric current is an alternating current.
- The system (8) according to claim 5, wherein the electric current is below 10 mA, below 1 mA, between 0.1 mA and 1 mA, or between 0.4 mA and 0.8 mA.
- The system (8) according to claim 5 or 6, wherein the electric current is supplied at a voltage between the first electrical connector (18) and the second electrical connector (19) that is below 80 V, below 50 V, between 10 V and 50 V, between 20 V and 50 V, or between 30 V and 50 V.
- The system (8) according to any of the claims 5-7, wherein the alternating current has a frequency between 1 kHz and 5 kHz.
- The system (8) according to any of the claims 1-8, wherein the power source (20) is further configured for supplying a pulsed electric current.
- The system (8) according to claim 9, wherein the pulses have a combined pulse length over a period of time that is equal to or less than 50% of the length of the period.
- The system (8) according to any of the claims 1-10, wherein the electrically conductive polymer material of the inner layer (12) is carbon-black filled polyethylene.
- The system (8) according to any of the claims 1-11, wherein the multilayered pipe (10) is a flexible hose.
- The system (8) according to claim 12, wherein the electrically conductive polymer material of the inner layer (12) is carbon-black filled polyethylene.
- A method for retrofitting a system (8) for preventing microbiological growth in an existing conduit for conveying a liquid, the method comprises:- providing a system (8) according to any of the claims 1-13,- providing the pipe (10) inside the existing conduit.
- A method for preventing microbiological growth in the pipe (10) of a system (8) according to any of the claims 1-13, wherein the pipe (10) conveys a liquid and the method comprises: supplying an electric current to the inner layer (12) of the pipe (10) with the electric power source (20).
Priority Applications (9)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP16196711.2A EP3315841B1 (en) | 2016-11-01 | 2016-11-01 | Reduction of microbiological growth in pipes |
JP2019545856A JP7048626B2 (en) | 2016-11-01 | 2017-11-01 | Reduction of microbial growth in tubes |
ES17800428T ES2910927T3 (en) | 2016-11-01 | 2017-11-01 | Reduction of microbiological growth in pipes |
EP17800428.9A EP3535511B1 (en) | 2016-11-01 | 2017-11-01 | Reduction of microbiological growth in pipes |
PL17800428T PL3535511T3 (en) | 2016-11-01 | 2017-11-01 | Reduction of microbiological growth in pipes |
DK17800428.9T DK3535511T3 (en) | 2016-11-01 | 2017-11-01 | REDUCTION OF MICROBIOLOGICAL GROWTH IN PIPES |
US16/345,594 US11454345B2 (en) | 2016-11-01 | 2017-11-01 | Reduction of microbiological growth in pipes |
CN201780068279.9A CN109906335B (en) | 2016-11-01 | 2017-11-01 | System and method for preventing microbial growth in a conduit transporting a liquid |
PCT/EP2017/077973 WO2018083127A1 (en) | 2016-11-01 | 2017-11-01 | Reduction of microbiological growth in pipes |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP16196711.2A EP3315841B1 (en) | 2016-11-01 | 2016-11-01 | Reduction of microbiological growth in pipes |
Publications (2)
Publication Number | Publication Date |
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EP3315841A1 EP3315841A1 (en) | 2018-05-02 |
EP3315841B1 true EP3315841B1 (en) | 2019-03-27 |
Family
ID=57249697
Family Applications (2)
Application Number | Title | Priority Date | Filing Date |
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EP16196711.2A Active EP3315841B1 (en) | 2016-11-01 | 2016-11-01 | Reduction of microbiological growth in pipes |
EP17800428.9A Active EP3535511B1 (en) | 2016-11-01 | 2017-11-01 | Reduction of microbiological growth in pipes |
Family Applications After (1)
Application Number | Title | Priority Date | Filing Date |
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EP17800428.9A Active EP3535511B1 (en) | 2016-11-01 | 2017-11-01 | Reduction of microbiological growth in pipes |
Country Status (8)
Country | Link |
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US (1) | US11454345B2 (en) |
EP (2) | EP3315841B1 (en) |
JP (1) | JP7048626B2 (en) |
CN (1) | CN109906335B (en) |
DK (1) | DK3535511T3 (en) |
ES (1) | ES2910927T3 (en) |
PL (1) | PL3535511T3 (en) |
WO (1) | WO2018083127A1 (en) |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
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WO2021069395A1 (en) * | 2019-10-07 | 2021-04-15 | Epff Electrical Pipe For Fluid Transport Ab | Prevention of microbiological growth in heat exchangers |
EP3805689A1 (en) * | 2019-10-07 | 2021-04-14 | EPFF Electrical Pipe For Fluid transport AB | Prevention of microbiological growth in heat exchangers |
US20210299399A1 (en) * | 2020-03-31 | 2021-09-30 | Peter Barrett | Active / passive anti-pathogen endotracheal tube |
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GB471318A (en) * | 1937-03-30 | 1937-09-01 | Karl A Zimmerer Mfg Company In | Improvements relating to apparatus, for preventing beer settling |
CA2145539C (en) * | 1992-09-25 | 2003-07-29 | Clive Barnes | Preventing contaminant build-up in beer lines |
JP3962846B2 (en) * | 1997-10-22 | 2007-08-22 | アタカ大機株式会社 | Antifouling method and antifouling device |
JPH11147598A (en) * | 1997-11-12 | 1999-06-02 | Leslie Philip Middleton David | Device and method for preventing growth of germ in drink transferring pipe and removing germ therefrom |
JP2002282810A (en) * | 2001-03-27 | 2002-10-02 | Daiki Engineering Kk | Contamination prevention device |
EP1273436A1 (en) * | 2001-07-05 | 2003-01-08 | Atofina Research S.A. | Glossy tubes and pipes |
US7094381B1 (en) * | 2003-01-08 | 2006-08-22 | James Michael Overton | Device for destroying microbes in a fluid |
JP2005074256A (en) | 2003-08-28 | 2005-03-24 | Jonan Kk | Method and device for preventing adhesion and deposition of organic matter to distributing pipe |
US20080053550A1 (en) * | 2006-08-30 | 2008-03-06 | Dayco Products, Llc | Multilayer hose construction |
GB2442011B (en) * | 2006-09-20 | 2011-09-14 | Cambridge Scientific Solutions Ltd | Fluid conveying conduit |
EP2052743A1 (en) | 2007-10-25 | 2009-04-29 | Carlsberg Breweries A/S | A beverage sterilisation device |
GB0800538D0 (en) * | 2008-01-11 | 2008-02-20 | Crompton Technology Group Ltd | Fuel pipes with controlled resistivity |
AT506089B1 (en) * | 2008-03-03 | 2009-06-15 | Ke Kelit Kunststoffwerk Gmbh | FORM BODY OF A POLYMER, PARTICULARLY TUBE |
US10132439B2 (en) | 2008-12-19 | 2018-11-20 | Epff Electrical Pipe For Fluid Transort Ab | Pipe and a method for reducing biofilms |
WO2012128771A1 (en) * | 2011-03-24 | 2012-09-27 | Empire Technology Development Llc | Fluid treatment method and system using flowing generator to treat water |
WO2013119511A1 (en) * | 2012-02-06 | 2013-08-15 | Elmedtech, LLC | Composition, method, and devices for reduction of cells in a volume of matter |
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2016
- 2016-11-01 EP EP16196711.2A patent/EP3315841B1/en active Active
-
2017
- 2017-11-01 PL PL17800428T patent/PL3535511T3/en unknown
- 2017-11-01 WO PCT/EP2017/077973 patent/WO2018083127A1/en unknown
- 2017-11-01 JP JP2019545856A patent/JP7048626B2/en active Active
- 2017-11-01 US US16/345,594 patent/US11454345B2/en active Active
- 2017-11-01 ES ES17800428T patent/ES2910927T3/en active Active
- 2017-11-01 EP EP17800428.9A patent/EP3535511B1/en active Active
- 2017-11-01 DK DK17800428.9T patent/DK3535511T3/en active
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Publication number | Publication date |
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DK3535511T3 (en) | 2022-04-04 |
JP2019535512A (en) | 2019-12-12 |
EP3535511A1 (en) | 2019-09-11 |
EP3315841A1 (en) | 2018-05-02 |
WO2018083127A1 (en) | 2018-05-11 |
US20190249815A1 (en) | 2019-08-15 |
CN109906335B (en) | 2021-03-19 |
US11454345B2 (en) | 2022-09-27 |
PL3535511T3 (en) | 2022-05-09 |
CN109906335A (en) | 2019-06-18 |
JP7048626B2 (en) | 2022-04-05 |
EP3535511B1 (en) | 2021-12-29 |
ES2910927T3 (en) | 2022-05-17 |
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